Many abnormal medical conditions in humans and other mammals have been associated with disease and other aberrations along the lining or walls that define several different body spaces. In order to treat such abnormal conditions of the body spaces, medical device technologies adapted for delivering various therapies to the body spaces using the least invasive means possible.
As used herein, the term “body space,” including derivatives thereof, is intended to mean any cavity within the body which is defined at least in part by a tissue wall. For example, the cardiac chambers, the uterus, the regions of the gastrointestinal tract, and the arterial or venous vessels are all considered illustrative examples of body spaces within the intended meaning.
The term “vessel,” including derivatives thereof, is herein intended to mean any body space which is circumscribed along a length by a tubular tissue wall and which terminates at each of two ends in at least one opening that communicates externally of the body space. For example, the large and small intestines, the vas deferens, the trachea, and the fallopian tubes are all illustrative examples of vessels within the intended meaning. Blood vessels are also herein considered vessels, including regions of the vascular tree between their branch points. More particularly, the pulmonary veins are vessels within the intended meaning, including the region of the pulmonary veins between the branched portions of their ostia along a left ventricle wall, although the wall tissue defining the ostia typically presents uniquely tapered lumenal shapes.
One means of treating body spaces in a minimally invasive manner is through the use of catheters to reach internal organs and vessels within a body space. Electrode or electrophysiology (EP) catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity. In use, the electrode catheter is inserted into a major vein or artery, e.g., the femoral artery, and then guided into the chamber of the heart that is of concern in order to perform mapping and ablation procedures. It is important to know and be able to map the location of the tip or other portions of such electrode catheters within the vessels or other locations in the body space.
U.S. Pat. Nos. 5,391,199, 5,443,489, 6,788,967 and 6,690,963 to Ben-Haim, whose disclosures are incorporated herein by reference, describe systems wherein the coordinates of an intrabody probe are determined using one or more field sensors, such as a Hall effect device, coils, or other antennae carried on the probe. Such systems are used for generating three-dimensional location information regarding a medical probe or catheter. Preferably, a sensor coil is placed in the catheter and generates signals in response to externally applied magnetic fields. The magnetic fields are generated by three radiator coils, fixed to an external reference frame in known, mutually spaced locations. The amplitudes of the signals generated in response to each of the radiator coil fields are detected and used to compute the location of the sensor coil. Each radiator coil is preferably driven by driver circuitry to generate a field at a known frequency, distinct from that of other radiator coils, so that the signals generated by the sensor coil may be separated by frequency into components corresponding to the different radiator coils.
In United States Patent Application No. 2007/0016007 filed by Govari and incorporated herein by reference, a hybrid position sensing system includes a probe adapted to be introduced into a body cavity of a subject. The probe includes a biosensor having a magnetic field transducer and at least one probe electrodes. A control unit is configured to measure position coordinates of the probe using the magnetic field transducer of the biosensor. The control unit also measures an impedance between the at least one probe electrodes and one or more points on a body surface of the subject. Using the measured position coordinates, the control unit calibrates the measured impedance.
Thus, in such a hybrid magnetic and impedance based systems, a biosensor and electrode must be placed at multiple points on the body surface of the patient. Because the biosensors and the electrical cabling connecting them to the EP mapping system are relatively expensive, it is ideal that the biosensors and the associated cable be reusable. The portion attached to the skin is preferably disposable, therefore, a disposable patch is necessary for affixing the reusable biosensor and possibly a portion of the electrode to the skin of the patient.
Existing patches comprises one or more stainless steel studs, foam and a conductive adhesive gel that is in contact with the skin of the patient. The matching patch cable in existing systems primarily comprise one or more matching stainless steel snaps into which the studs of the patch mate, a biosensor and the associated electrical cable all housed in an epoxy shell. Existing biosensor cable and patch mechanisms are radiopaque, i.e., the stainless steel snaps and studs appear on fluoroscopy. When multiple snaps are used which is often the case in order to provide a secure and non-rotating connection between the patch and the sensor cable, the multiple snaps do not allow the patch to take the shape of the body. Also, the patches are often large and conflict with other patches used on the body for ECG, defibrillators, intra-cardiac echograms, etc.
Notably, U.S. Pat. No. 3,606,881, relates to a disposable patch having a metallic terminal with an enlarged head which permits a squeeze activated clip to be secured around the metallic terminal. U.S. Pat. No. 3,829,826 provides a mechanical mechanism for attaching to the standard male metallic snap of the standard ECG patch. U.S. Pat. No. 4,490,005 relates to a patch in which the central stud is a metal coated non-metallic substrate and which permits rotation of the sensor cable while reducing the effect of rotation on the metal to metal connection. U.S. Pat. No. 4,635,642 relates to a disposable pad in which a conductive, preferably, silver coated metallic stud is inserted in order to make electrical conduct with a gel matrix that is in contact with the skin of the patient.
A similar conductively coated electrically conductive plastic is provided in U.S. Pat. No. 5,499,628 as an eyelet that is press fit into a terminal made of a resilient nonmetallic composition such as polypropylene blended with carbon fiber. Additionally, U.S. Pat. No. 5,615,674 relates to a clamping contact connection for contacting a fetal scalp probe. U.S. Pat. No. 5,782,761 relates to a molded electrode one-piece and two-piece constructions for a molded electrode made of a conductive material such as a carbon-filled plastic. U.S. Pat. No. 6,650,922 relates to an electrode element made of an electrode made of a biodegradable material that is also electro conductive. U.S. Pat. No. 6,780,065 relates to a device for electrical connection of the power lead to an electrode for use on the skin. U.S. Pat. No. 7,226,299 relates to a circular electrical connector that engages the socket of a female connector that may include a locking device having resilient prongs. Design Pat. 240,166 relates to a medical electrode with a rectangular cube portion. U.S. Patent Application Publication No. 2006/0167354 relates to a system for connecting an electrode to a conductive cable. U.S. Patent Application Publication No. 2006/0149146 relates to a device having an electrode for contact with the patient and a pressure sensor. U.S. Pat. No. 5,978,693 relates to an electrode having a deformation sensor such as a strain gauge.
U.S. patent application Ser. No. 12/256,580, now U.S. Patent Publication No. 2009/0318793, the entire disclosure of which is hereby incorporated by reference, relates to a patch and sensor assembly with a disposable portion and a reusable portion, each having a respective cable for connection to a mapping and localization system.
It is an object of the present invention to provide a patch that is generally not visible under fluoroscopy. It is a further object of the present invention that the patch be capable of being smaller than currently used patches so as to minimize the amount of space used on the skin of the patient and reduce potential conflict with other patches. Additionally, it is an object of the present invention to provide a patch and sensor cable that will not rotate as would previous designs utilizing a single snap. Furthermore, it is an object of the present invention to have a patch and sensor cable attachment mechanism that is easy to attach. Additionally, it is an object of the present invention to have a patch and sensor cable design that could be used for ECG or other instrument systems. Moreover, it is an object of the present invention to have a patch and sensor cable attachment mechanism that enables repeated reuse of the biosensor and sensor cable without any degradation in performance. Finally, it is an object of the present invention to provide a single cable attachment for both the biosensor and electrode of a given patch.